Resistance member adjusting mechanism of abrasive type grain whitening machines

Abstract: An abrasive type vertical grain milling machine (4) comprises a perforated cylindrical body (42) which serves to define an outer periphery of a grain milling chamber and which has a plurality of vertically arranged resistance members (53) projected radially into the grain milling chamber so as to impart resistances to motions of the grains in a circumferential direction of an abrasive type roll assembly, an amount of projections of each of the resistance members (53) being made to be adjustable, and further has projection amount adjusting mechanisms (45) for adjusting independently the respective amounts of projection in the radial direction of the plural resistance members (53) located in different vertical positions, and therefore, it is possible to adjust independently the resistance imparted to the motions of the grains within the grain milling chamber in each of the upstream-side region and downstream-side region of the grain milling chamber.

Description: The present invention refers to an abrasive type vertical grain milling machine comprising: an abrasive type grain milling roll assembly mounted on a main shaft extending straight in a vertical direction; and a perforated cylindrical body extending vertically around said roll assembly leaving a space therefrom so as to define a cylindrical grain milling chamber around said roll assembly in cooperation with an outer peripheral surface of said roll assembly and having a large number of holes through which bran produced in said grain milling chamber is allowed to be released, the grain milling chamber having a vertical one end where grains to be milled are introduced and another end from where grains having been milled are discharged, said cylindrical body comprises a plurality of vertically arranged resistance members projected radially into the grain milling chamber so as to impart resistances to motions of the grains in a circumferential direction of said roll assembly, an amount of projection of each of said resistance members being made to be adjustable, and projection amount adjusting means for adjusting independently the respective amounts of projection in the radial direction of said plural resistance members located in different vertical positions, said cylindrical body comprises a plurality of stanchions circumferentially spaced apart from each other and extending substantially in the vertical direction, and perforated arcuate plate members, disposed between the circumferentially adjacent stanchions and each forming a part of a cylinder of said cylindrical body, and said plural stanchions so as to be located in different vertical positions on a side of the associated stanchion facing to the grain milling chamber through said projection amount adjusting means while being movable in the radial direction of said roll assembly with respect to the associated stanchion. Such an abrasive type vertical grain milling machine is known from CH-A-280080. In a grain milling machine, the grains to be milled, such as rice grains, are introduced into the milling or whitening chamber from an upper end thereof. The grains are forcibly rotated in a circumferential direction by the grain milling roll assembly. The rice grains rub against each other and other surfaces thereof are scraped so that they are milled, or whitened. Rubbing between the rice grains becomes more intense as the amount of the projection of the resistance members is increased to impart a higher resistance to the movement of the rice grains in a circumferential direction, which results in the milling or whitening action being performed more powerfully. However, since the size of the rice grains become smaller with the progress of the milling, or whitening of the rice grain, and the steady state of the machine when the rice grains are supplied at a constant flow rate, for example, the resistance imparted to the movement of the flow of the rice grains becomes smaller in the downstream-side region of the whitening chamber as compared with the upstream-side region of the same. Accordingly, there is a possibility that in the downstream-side region, since the intensity of the rubbing between the rice grains, which depend on the amount of projection of the resistance members, becomes lower as compared with the upstream-side region, it becomes hardly possible to achieve a sufficient whitening action. In an abrasive type grain milling machine, this tendency is remarkable. In the case of use of a resistance member adjusting means, it may become difficult to adjust the mechanism during the whitening action. The grain milling machine, according to CH-A-280080, is, therefore, provided with several independently adjustable resistance members located in different vertical positions. The resistance members are of equal size and have to be adjusted individually. Adjusting these resistance members, however, is rather time-consuming, particularly if different grains have to be milled and the machine has to be adjusted accordingly. There has, therefore, been a need for an abrasive type vertical grain milling machine. according to the afore-mentioned type, that allows easier adjustment of the resistance members for milling different kinds of grains. The object has been achieved, according to an abrasive type vertical grain milling machine of the afore-mentioned type, wherein resistance members in different positions are different in length. This allows as easy adjustment of the different resistance members according to the milling profile. For example, shorter resistance members on the upstream side allow a fine adjustment of the distance between the roll assembly and the resistance members compared to the downstream side. Also, the number of resistance members on the downstream side is, then, fewer than on the upstream side and, therefore, requires only a minimum number of resistance members to be adjusted. According to the present invention, it is preferred that each of the plural resistance members supported by said each stanchion extends in the vertical direction and a distance between adjacent end portions of the vertically adjacent resistance members is smaller than a size of the grains to be milled. In this case, there is no possibility that the small gap between the adjacent end portions of the resistance members is clogged with the grains and the like. According to the present invention, it is preferred that each of the stanchions has a substantially U-letter form cross-section and a concave portion of the "U" faces toward the roll assembly so that the plural resistance members supported by said each stanchion are located within the concave portion at radially outward parts thereof with respect to the roll assembly. In this case, the positions of the plural resistance members can be easily adjusted independently with a relatively simple construction. According to the present invention, it is preferred that the projection amount adjusting means is adapted to be able to make each of the resistance members project radially inwardly until the resistance member is brought into contact with the outer peripheral surface of the roll assembly. In this case, even the milling of for example the grains the average size of which is different can be performed by adjusting the radial position(s) of the resistance member(s). According to the present invention, it is preferred that the roll assembly comprises a plurality of roll elements fitted on the main shaft while being spaced from each other in the vertical direction in which the main shaft extends, and adjacent end portions of the vertically adjacent resistance members defines a small gap therebetween at a level of the space between the roll elements. In this case, there is little possibility that the grains are pressed into the small gap owing to the pressing force applied to the grains by the roll elements during the abrasive operation. Further, it is also possible that the roll assembly comprises a plurality of roll elements fitted on the main shaft while being spaced from each other in the vertical direction in which the main shaft extends, and adjacent end portions of the vertically adjacent resistance members defines a small gap therebetween at a level where it faces to the outer peripheral surface of one of the roll elements. In this case, it is necessary or desired to make the gap between the both upper and lower resistance members as small as possible. Moreover, the amount of projection of each resistance member at the upstream and downstream ends thereof may be different. For example, a single resistance member may be so disposed as to project the more as going toward the downstream side. In this case, the distance between the surface of the roll assembly and the resistance member is suitably changed in accordance with the details of the desired grain milling action. The foregoing and other objects, features as well as advantages of the invention will be made clearer hereafter from detailed description of preferred embodiments with reference to drawings. BRIEF DESCRIPTION OF DRAWINGS Figure 1 is a vertical sectional view of an abrasive type vertical grain milling machine according to a preferred embodiment of the present invention (or a sectional view of Figure 3 taken along the line I-I); Figure 2 is an enlarged sectional view of a part of the grain milling machine of Figure 1; Figure 3 is a cross-sectional view of the grain milling machine of Figure 1 taken along the line III-III; Figure 4 is an explanatory view showing, in exaggeration, relation (distance relation) between resistance claws and an abrasive roll assembly of the grain milling machine of Figure 1; Figure 5 is an explanatory view of a modification of the arrangement of the resistance claws shown in Figure 4; Figure 6 is an explanatory view of another modification of the arrangement of the resistance claws shown in Figure 4; Figure 7 is an explanatory view of still another modification of the arrangement of the resistance claws shown in Figure 4; and Figure 8 is an explanatory view showing relation between an abrasive roll assembly and a feed roll in a modification of the abrasive type vertical grain milling machine of Figure 1. DESCRIPTION OF PREFERRED EMBODIMENTS Next, taking a case of milling or whitening rice grain as an example of cereal grain, an abrasive type vertical rice whitening machine, which is a preferred embodiment of an abrasive type vertical grain milling machine according to the present invention, will be described with reference to Figures 1 to 4. In Figure 1 which is a general vertical sectional view of an abrasive type vertical rice whitening machine 1, reference numeral 2 denotes a base. In the central portion of the base 2, a main shaft 3 constituted by a hollow shaft extending in the vertical direction is rotatably supported by means of upper and lower bearings 4 and 5. A motor 6 is equipped sidewards of the base 2 so that rotation of an output shaft 7 of the motor 6 is transmitted through a pulley 8, a wedge belt or V belt 9 and a pulley 10 to the main shaft 3, thereby making the main shaft 3 rotate at a suitable rotational speed (generally at a rotational speed where a peripheral speed of an abrasive type roll assembly 16 to be described later becomes about 600 m/min at an outer peripheral surface thereof). A lower rotary bottom member 11 having a cap-like cross-section is fixed to the main shaft 3 such as to be positioned above the upper bearing 4, and an upper rotary bottom member 13 formed with stirring blades 12 serving to discharge the whitened or milled white rice is fixed to the lower rotary bottom member 11. The upper rotary bottom member 13 has a radially outward flange portion 17 on which is supported a bottom portion of the abrasive type roll assembly 16 constituted by a stack of a large number of abrasive type roll elements 14 with roll element spacers 15 interposed therebetween. Each roll element 14 comprises a rigid abrasive cylinder support member 24 including a boss portion 21 fitted on the main shaft 3, a plurality of arm portions 22 formed integrally with the boss portion 21 and extending radially outwardly from the boss portion 21 and a cylindrical portion 23 formed integrally with the extended ends of the arm portions 22, and an abrasive cylinder 26 securely fixed to the support member 24 and formed by an aggragate of emery particles (Carborundom (trademark)). Incidentally, among the abrasive cylinders 26, the uppermost abrasive cylinder, that is, an abrasive cylinder 26a located on the most upstream side of the flowing direction of rice grains to be whitened, is formed in the shape of a circular truncated cone in order to guide the rice grains or the flow of rice grains. Further, the hollow main shaft 3 is formed with a large number of air holes 29 in the portion thereof where the abrasive type roll assembly is fitted on, and the boss portion 21 of the abrasive cylinder support member 24 of each of the roll elements 14 is also formed therein with air holes 30. Accordingly, in case that the abrasive cylinder support member 24 of the roll element 14 is fitted on the hollow main shaft 3, at least a part of the air holes 30 formed in each boss portion 21 are communicated with at least a part of the air holes 29 formed in the main shaft 3, thereby enabling air to flow from an interior space 31 of the hollow main shaft 3 to the inside of the abrasive cylinder 26 through the air holes 29 and 30. On the other hand, each of the roll element spacers 15 comprises, as shown in Figure 3, a boss portion 32 having a larger outer diameter than the boss portion 21 and a plurality of arm portions 33 formed integrally with the boss portion 32 and extending substantially radially outwardly from the boss portion 32. Each arm portion 33 comprises a base-side arm portion 34 extending straight in the radial direction and a tapered tip end-side arm portion 35 extending radially outwardly from the end of the base-side arm portion 34 as turning aside in the direction opposite to the direction of rotation of the spacer 15. Accordingly, the air having flown out from the interior space 31 of the hollow main shaft 3 to the inside of the abrasive cylinder 26 through the air holes 29 and 30 can flow out through spaces 36 defined between the adjacent arm portions 33 and 33 of every roll element spacer 15 and through between the adjacent roll elements 14 and 14. In other words, the spaces 36 serve as the bran removing jet-air outlets of the abrasive type roll assembly 16. Around the abrasive type roll assembly 16 is disposed a porous or perforated cylindrical body 42 which cooperates with the outer peripheral surface of the roll assembly 16 to form a cylindrical grain milling chamber or a rice whitening chamber 40 around the roll assembly 16. The porous cylindrical body 42 extends vertically leaving a space from the roll assembly 16 and has a large number of holes 41 through which bran produced in the rice whitening chamber 40 is allowed to be released. Around the porous cylindrical body 42 is disposed a cylindrical cover 44 which cooperates with the porous cylindrical body 42 to define a bran removing chamber 43 serving to collect and discharge the bran. The porous cylindrical body 42 and the cylindrical cover 44 are set on and fixed to a double-cylindrical support member 2a fixed to the base 2. The double-cylindrical support member 2a comprises an outer cylindrical support portion 2b fixed to the base 2 at a bottom flange thereof, ribs 2c projecting inwardly from the outer cylindrical support portion 2b at four circumferential points and an inner cylindrical support portion 2d formed integral with the outer cylindrical support portion 2b through the ribs 2c. As shown in Figure 3, the porous cylindrical body 42 comprises four resistance imparting-adjusting mechanisms 45 disposed in such circumferential positions that the cylinder defined by the cylindrical body 42 is divided into four equal parts, and metallic porous or perforated arcuate plate members 46 serving to define the cylindrical surface portions between the adjacent resistance imparting-adjusting mechanisms 45 and 45. Accordingly, the bran removing chamber 43 is divided into four sections or four chambers by the four resistance imparting-adjusting mechanisms 45. The number of the resistance imparting-adjusting mechanisms 45 may be either not greater than 3 or not smaller than 5. The plural resistance imparting-adjusting mechanisms 45 are arranged equidistantly in the circumferential direction of the cylindrical body 42 as shown in Figure 3, for example. Further, as seen from Figures 1 and 2, the flow resistance imparting-adjusting mechanisms 45 and the porous arcuate plate members 46 are respectively formed to extend over the entire vertical length of the rice whitening chamber 40. A distance H between the inner peripheral surface of the porous plate member 46 and the outer peripheral surface of the abrasive roll element 14 is in the range of about 10 ∼ 15 mm, for example. The distance H is decided in accordance with the kind of grain to be milled, size of emery particles of the abrasive roll element 14, rotational speed of the abrasive roll element 14 and the like. Each flow resistance imparting-adjusting mechanism 45 comprises a stanchion or support post 51 of a substantially U-letter form cross-section extending in the vertical direction and set on and fixed to upper ends of the ribs 21c through a bottom plate 50, prismatic resistance claws 53a and 53b made of for example rubber and fitted disengageably in a concave portion 52, which extends in the vertical direction of "U" of each stanchion 51 and opens radially inwardly, so as to serve as upper and lower resistance members (in case of generally calling the upper and lower resistance claws, they are designated by the reference numeral 53), knob bolts 57 as adjusting member screwed in upper and lower tapped holes 54 and 55 of the respective resistance claws 53 at external thread portions 56 thereof so as to adjust the radial positions of the resistance claws 53 with respect to the stanchion 51 (in other words, distances J1 and J2 between the upper and lower resistance claws 53a, 53b and the abrasive roll element 14 (in case of generally calling, these distances are designated by the reference character J)), and set bolts 59 screwed in tapped holes of the stanchion 51 for serving, after the adjustment of the positions of the resistance claws 53, to fix the resistance claws 53 with respect to the stanchion 51 by making the tip ends thereof come in contact with an outside end faces 58 of the resistance claws 53 (hereinafter, suffixes a and b will be added, as occasion demands, even in case of describing about the member or portion which is provided equally to the upper and lower resistance members such as the knob bolt 57 and the set bolt 59, that is, the suffix a will be added for the members or portions associated with the upper resistance claw while the suffix b for the members or portions associated with the lower resistance claw). The resistance claws 53 may be made of a plastic or metallic material having suitable strength and hardness, in place of rubber. In more detail, prismatic reinforcing pieces 62, 62 having enhanced wear proof property by quenching are screwed to the stanchion 51 at the inner peripheral ends of the stanchion 51 and on both sides of the concave portion 52, thereby forming a stanchion assembly 63 as a whole. Incidentally, each reinforcing piece 62 projects a little radially inward beyond the porous arcuate plate member 46 bent in the form of a circular arc by about 2 mm, for example. On the other hand, circumferential end edge portions 46a and 46b of each porous arcuate plate member 46 are pressed on and fixed to side walls of the associated stanchion assemblies 63 by means of stiffening plates 64. Reference numeral 66 denotes hollow stud bolts. A small diameter external thread portion 66a of the bolt 66 is screwed in the tapped hole of the stanchion 51, while a nut 68 serving to fix a cover 67 is screwed to a large diameter external thread portion 66b of the bolt 66. On the other hand, the external thread portion 56 of the knob bolt 57 is loosely fitted in a small diameter portion 69a of a hole 69 of the hollow bolt 66, while a large diameter portion 57A of the knob bolt 57 is rotatably inserted in a large diameter portion 69b of the hole 69. Incidentally, in a state that an end face 57B of the large diameter portion 57A of the knob bolt 57 is in contact with a stepped portion 69c of the wall of the hole 69, a stopper ring 70 is fitted in an annular groove 57C of the knob bolt 57 and the end portion of the stud bolt 66 is caulked, thereby prohibiting the knob bolt 57 from displacing in the axial direction thereof with respect to the bolt 66 and, hence, to the stanchion 51. In case of adjusting the distance J between the resistance claw 53 and the roll element 14, the set bolt 59 is first unfastened or loosened and, then, the knob bolts 57 screwed respectively in the tapped holes 54 of the stanchion 51 are turned so as to make the upper and lower portions of the resistance claw 53 come close to and away from the roll element 14 by a specified length. Subsequently, the set bolt 59 is fastened again finally. Usually, in order to make the resistance claw 53 extend substantially exactly in the vertical direction, angles through which the knob bolts 57 are turned with respect to the tapped holes 54 for adjustment are made equal to each other. However, if desired, the angles through which the knob bolts 57, 57 are turned with respect to the tapped holes 54, 55 for adjustment may be differed from each other so as to slightly incline the resistance claw 53 in such a manner that the distance J between the resistance claw 53 and the abrasive roll assembly 16 becomes smaller or larger as going downwards, for example. In this case, a vertical discrepancy (or the angle of inclination) is small as compared with the length of the resistance claw 53. The above operation of adjusting the position of the resistance claw is performed independently for each of the upper and lower resistance claws 53a and 53b by handling or operating the associated knob bolts 57a, 57b and the set bolts 59a, 59b, respectively. For instance, in case that there is a possibility that an intensity of pressing the rice grains is lowered as going downwards in the rice whitening chamber 40 with the progress of the whitening of the surface of rice grains because the bran can be easily removed from the rice whitening chamber 40 sufficiently, the distance J1 between the upper resistance claw 53a and the abrasive roll assembly 16 is made larger than the distance J2 between the lower resistance claw 53b and the abrasive roll assembly 16 (see Figure 4). On the other hand, in case that it is difficult to remove the bran sufficiently and hence the bran is apt to be collected in a lower part of the rice whitening chamber 40, the distance J1 between the upper resistance claw 53a and the abrasive roll assembly 16 is made smaller than the distance J2 between the lower resistance claw 53b and the abrasive roll assembly 16. Incidentally, in selecting and setting the distances J1, J2 between the upper and lower resistance claws 53a, 53b and the abrasive roll assembly 16, other various reasons or conditions as desired are taken into consideration. Further, in the case shown in Figures 1 to 4, the upper resistance claw 53 is shorter in vertical length than the lower resistance claw 53b, and however, the length of the upper resistance claw 53a may be made longer than the length of the lower resistance claw 53b as shown in Figure 5. Moreover, as shown by imaginary line 80 in Figure 4, the resistance member 53 may be formed therein with grooves at positions thereof facing to the jet-air outlets 36 in order to prevent the jet-air outlets 36 and the vicinity thereof from being clogged with the rice grains. In addition, in the case illustrated in Figures 1 and 2, a small gap 72 between the lower end of the upper resistance claw 53a and the upper end of the lower resistance claw 53b is situated just at a level facing to the jet-air outlet 36 between the roll elements 14, 14, and however, as shown by imaginary line 72a in Figure 4, the lengths of the upper and lower resistance claws 53a and 53b may be so selected as to form the gap 72a at a level where it faces to the outer peripheral surface of one of the plural roll elements 14. Incidentally, although the resistance claw 53 is shown as being extended over the entire length of the rice whitening chamber 40, it may be so provided as to extend over a part of the entire length of the same, that is, it may be so provided as to be present in a region not higher than a level of imaginary line 79 as shown in Figure 4, for example. Further, the size of the gap 72 is selected to be in a range which can eliminate a possibility that the rice grains are caught or taken in the gap to hinder the flow of the rice grains to be whitened. Moreover, as shown by imaginary line 72b in Figure 4, at least one of the lower end of the upper resistance claw 53a and the upper end of the lower resistance claw 53b may be tapered or rounded. In addition, the number of the resistance claws 53 which are supported substantially in series by a single stanchion assembly 63 and have their positions adjusted by the knob bolts 57 and the set bolt 59 individually or independently may be three as shown in Figure 3 or more, in place of two. Further, in the above description, the two resistance claws 53a and 53b provided in every four circumferential points are assumed to have the same length and the same configuration, respectively, and however, the resistance claws 53 provided in at least one of four circumferential points, e.g., in all of the four points, may be made of different combination of the resistance claws 53a, 53b and the like, as shown in Figure 7. In the case shown in Figures 6 and 7, the resistance imparted to the flow of rice grains can be adjusted or changed delicately as the more than two resistance claws are held in vertical positions. Referring back to Figure 3, as shown therein in detail, the cylindrical cover 44 serving as an outer peripheral wall of the bran removing chamber 43 has fitting portions 74 in portions thereof corresponding to the knob bolts 57, and an outer cover 76 of the knob bolt 57 is fitted in a bent portion 75 of each of the fitting portions 74. An outer surface 76a of the cover 76 is marked with a scale which shows the adjusted distance J of the resistance claw 53 proportional to the turning angle of the knob bolt 57 for adjustment. Incidentally, each of the bent portions 75 of the cover 44 is further extended so as to cover around the movable portion of the knob bolt 57 within the bran removing chamber 43. Each of the extended portions 77 is further fitted detachably on a fixed seat 78 of the stanchion 51. Referring back to Figures 1 and 2, reference numeral 81 denotes a hollow bottomless feed roll having a feed screw on the outer peripheral surface thereof. The feed roll 81 is set on the uppermost roll element 14 while being fitted at a boss portion 81a thereof on the main shaft 3 and securely fixed to the main shaft 3 together with the abrasive roll assembly 16 by means of a bolt 82 screwed in a tapped hole in the upper end of the main shaft 3. Further, reference numeral 83 denotes a feed cylinder which forms a supply chamber 84 of the rice grains to be whitened in cooperation with the feed roll 81, and a flange portion 83a at the lower end of the feed cylinder 83 is set on and fixed to the upper end of the stanchion 51 and the cylindrical cover 44 as a part of the frame of the rice whitening machine 1. In addition, reference numeral 86 denotes a hopper into which the rice grains to be whitened are thrown, 87 denotes an upper rice grain guide member, and 88 denotes a feed amount regulating gate. The gate 88 is operated manually through a handle 89 or automatically by a motor 90 so as to adjust a position of a movable plate 91 with an opening 91a with respect to a bottom opening 86a of the hopper 86, so that the amount of rice grains to be fed from the hopper 86 into the supply chamber 84 is regulated. Reference numeral 92 denotes a lower guide member serving to feed the rice grains introduced through the gate 88 into the supply chamber 84 while dispersing the same. Reference numeral 95 denotes a resistance board provided at a discharge port 96 through which the rice grains having been whitened in the rice whitening chamber 40 are discharged. A pressing force applied to the rice grains in the rice whitening chamber 40 by the resistance board 95 is regulated by adjusting the position of a weight 99 screwed to one arm 98a of a lever 98 supported by a pivot shaft 97 by means of a handle (knob) 100. Numeral 101 denotes an expansion spring 101. Reference numeral 103 denotes a bran collecting fan which serves to release through an exhaust pipe 105 the bran collected in a bran collecting chamber 104 formed at the bottom of the bran removing chamber 43. Incidentally, a bottom cylindrical member 106 defining the inner peripheral wall of the bran collecting chamber 104 is fixed to the lower rotary bottom member 11, and the bottom cylindrical member 106 is provided with discharge blades 107 serving to promote the discharge of the bran from the bran collecting chamber 104 when the bottom cylindrical member 106 is rotated together with the lower rotary bottom member 11. Next, description will be given of handling and operation of the rice whitening machine 1 thus constructed which is a preferred embodiment of the abrasive type vertical grain milling machine according to the present invention, with reference to Figures 1 to 4. First, the rice whitening conditions of the abrasive type vertical rice whitening machine 1 are set and adjusted in accordance with the characteristics or properties of the rice grains to be whitened. More specifically, in accordance with various properties such as the shape of grain determined by the sizes of the rice grains to be whitened in both directions of long (minor) and short (minor) axes thereof before rice whitening, the average sizes of the rice grains in both directions of long and short axes thereof obtained after rice whitening, and the thickness and hardness of the surface layer of rice grain to be removed by the rice whitening machine 1, the radial positions of the resistance claws 53a and 53b are adjusted by handling the knob bolts 57 and the set bolts 59 while considering the diameter and rotational speed of the abrasive roll assembly 16, the abrasive characteristic of the abrasive roll element 14, the bran removing characteristic of the bran removing system including the exhaust fan 103 and so on. The distance J1 between the upper resistance claw 53a and the abrasive roll element 14 is adjusted and set mainly in accordance with relationship between sizes of the rice grains to be whitened in both directions of long and short axes thereof before rice whitening and desired sizes of the rice grains after rice whitening, while the distance J2 between the lower resistance claw 53b and the abrasive roll element 14, that is, a difference (J1 - J2) in radial position between the lower resistance claw 53b and the upper resistance claw 53a is adjusted and set mainly in accordance with the desired sizes (generally, shape) of the rice grains in both directions of long and short axes thereof obtained after rice whitening. Incidentally, the distance J2 between the lower resistance claw 53b and the abrasive roll element 14 is generally set to be rather large with the decrease of the hardness of the surface layer to be removed by the rice whitening machine 1. The above adjustment of the distances J1 and J2 may be even performed during the rice whitening operation while stopping the rotation of the abrasive roll assembly 16 (or while permitting the roll assembly 16 to rotate under certain circumstances). On the other hand, by adjusting the position of the weight 99 on the lever 98a by turning the knob 100, the pressing force resulting from the resistance board 95, that is, the pressure applied to the rice grains in the rice whitening chamber 40 by the resistance board 95 is regulated. Incidentally, this pressure regulation may be performed during the rice whitening as well. After the initialization described above, the cover 86b is opened and the rice grains to be whitened are thrown into the hopper 86 as the gate 88 is being closed and, at the same time, the motor 6 is started to rotate the abrasive roll assembly 16 and the feed roll 81 through the main shaft 3, with a result that the exhaust fan 103 is started so as to begin blowing of air for bran removing. Subsequently, the handle 89 or the motor 90 is operated to open the feed amount regulating gate 88 so that the rice grains to be whitened are started to be introduced into the supply chamber 84 from the hopper 86. In this case, the rice grains are supplied continuously into the supply chamber 84 as being dispersed uniformly in the circumferential direction by means of the upper and lower guide members 87 and 92. The rice grains received in the supply chamber 84 are fed continuously to an upper end 40c of the rice whitening chamber 40 by means of the feed roll 81. In the steady state of the rice whitening operation of the rice whitening machine 1, the rice grains supplied in the rice whitening chamber 40 come downwards gradually while repeating intermittent rolling and rotating or revolving (or moving around the main shaft in circular motion) between the stationary porous or perforated cylindrical body 42 and the rotating abrasive roll assembly 16 under the relatively low pressing force, during which the surface of the rice grains is made to come in contact with the abrasive cylinder 26 of the roll element 14 of the abrasive roll assembly 16 so as to be scraped off by the abrasive cylinder 26. In more detail, since the rice grains are caught between the resistance claws 53a and the abrasive roll assembly 16 when they reach the resistance claws 53a, the rotating or revolving speed thereof is reduced under the influence of braking action and a large difference comes out between the rotating (revolving) speed thereof and the rotational speed of the abrasive roll assembly 16, with a result that the surface of the rice grains is scraped off by being rubbed intensively with the emery particles of the abrasive cylinder 26 of the roll assembly 16. Further, since the resistance claws 53a have the function of braking the general or collective flow of the rice grains in the rice whitening chamber 40, the rolling speed and the rotating speed of the rice grains in the rice whitening chamber 40 are changed intermittently, with a result that the rice whitening proceeds gradually. Moreover, since the relation between the rolling speed and the rotating or revolving speed of the rice grains can be changed delicately by the adjustment of the resistance claws 53a, the shape of the rice grains to be discharged after whitening can be also changed by making use of this relation. When the rice grains, which have been partially whitened in the upper part 40a of the rice whitening chamber 40 and hence a little reduced in size, reach a lower part 40b of the rice whitening chamber 40, they receive the whitening action by the resistance claws 53b in a different way from the resistance claws 53a because, as seen from the above description, the distance J2 between the resistance claws 53b and the abrasive roll elements 14 is set to a suitable value which is different from the distance J1 between the resistance claws 53a and the abrasive roll elements 14. Accordingly, it is possible to perform the desired rice whitening not only in the upper part 40a but also in the lower part 40b of the rice whitening chamber 40. In addition, since a specified exit pressure is applied to the rice whitening chamber 40 by the resistance board 95 which is applied with the force of the weight 99, in case of whitening the rice grains in the aforementioned manner, the rice grains are abraded and whitened in the state that they are filled in the rice whitening chamber 40 at a suitable density so far as the rice grains are allowed to flow continuously. The rice grains having been whitened are collected in a collector portion 108 below a lower end 40d of the rice whitening chamber 40. The rice grains in the collector portion 108 are gathered in a stacker 112 through a chute 111 by opening the bottom resistance board 95 against the pressing force of the weight 99 while being stirred by the rotary stirring blades 12 attached to the lower rotary bottom member 11. Meanwhile, as the exhaust fan 103 is operated, air is flow out or exhausted through the exhaust pipe 105. Therefore, there is generated a stream or flow of air passing through the inside passage 31 of the main shaft 3, the air holes 29 and 30, the jet-air outlets 36, the rice whitening chamber 40, the holes 41 of the porous or perforated cylindrical body 42 and the bran removing chamber 43 in the mentioned order. Owing to this stream of air, the powdered matter such as bran having been produced in the rice whitening chamber 40 during the rice whitening is discharged to the bran removing chamber 43 through the holes or perforations 41 of the porous cylindrical body 42. Further, the stream of air within the rice whitening chamber 40 serves to suppress rise of temperature of the rice grains in the rice whitening chamber 40. In addition, the stream of air coming from the jet-air outlets 36 serves to remove the bran and the like matter also from the gap 72 between the resistance claws 53a and 53b. The bran having been introduced in the bran removing chamber 43 is collected in the bran collecting chamber 104 and discharged by the discharge blades 107. Further, the hopper 86 is also formed with an airflow passage (not shown) so that air having passed through this airflow passage into the hopper 86 also serves to assist the discharge of the bran from the rice whitening chamber 40. Moreover, the bran which comes in to the depth of the jet-air outlets 36 can be returned into the rice whitening chamber 40 due to the centrifugal force resulting from the rotation of the arms 33 as well as the air stream or flow. The above description has been made as to the case that the rice grains are whitened while being made to flow from top to bottom, and however, an abrasive type vertical rice whitening machine of a lift type is also available in which the feed roll 81 is disposed under the abrasive roll assembly 16 so that the rice grains are whitened while being made to flow from bottom to top in the upward direction of an arrow mark A as shown in Figure 8. The grain to be milled may be other grain such as wheat grain in place of rice grain. In this case, the grain milling conditions of the grain milling machine are changed in accordance with the grain size originating diffences in kind of grains as well as with the thickness, hardness and the like of the surface layer to be removed. Incidentally, the position adjusting mechanism of the resistance claw may be for example a piston-cylinder assembly and other like means in place of the knob bolt employed in the illustrated embodiment. Further, these may be the ones which are driven electrically or by fluid pressure.

Claims: An abrasive type vertical grain milling machine comprising: an abrasive type grain milling roll assembly (16) mounted on a main shaft (3) extending straight in a vertical direction; and a perforated cylindrical body (42) extending vertically around said roll assembly leaving a space therefrom so as to define a cylindrical grain milling chamber (40) around said roll assembly in cooperation with an outer peripheral surface of said roll assembly and having a large number of holes through which bran produced in said grain milling chamber is allowed to be released, the grain milling chamber having a vertical one end where grains to be milled are introduced and another end from where grains having been milled are discharged, said cylindrical body comprises a plurality of vertically arranged resistance members (53) projected radially into the grain milling chamber so as to impart resistances to motions of the grains in a circumferential direction of said roll assembly an amount of projection of each of said resistance members being made to be adjustable, and projection amount adjusting means (45) for adjusting independently the respective amounts of projection in the radial direction of said plural resistance members located in different vertical positions, said cylindrical body comprises a plurality of stanchions (51) circumferentially spaced apart from each other and extending substantially in the vertical direction, and perforated arcuate plate members (46), disposed between the circumferentially adjacent stanchions and each forming a part of a cylinder of said cylindrical body, and said plural stanchions so as to be located in different vertical positions on a side of the associated stanchion facing to the grain milling chamber through said projection amount adjusting means while being movable in the radial direction of said roll assembly with respect to the associated stanchion wherein resistance members in different verticle positions are different in length. An abrasive type verticle grain milling machine according to Claim 1, wherein a vertical length of a resistance member located on an upstream side in a direction of flow of the grains to be milled is shorter than that of a resistance member on a downstream side. An abrasive type vertical grain milling machine according to Claim 1 or 2, wherein each of the plural resistance members supported by said each stanchion extends in the vertical direction and a distance between adjacent end portions of the vertically adjacent resistance members is smaller than a size of the grains to be milled. An abrasive type vertical grain milling machine according to Claim 3, wherein each of the stanchions (51) has a substantially U-letter form cross-section and a concave portion (52) of the "U" faces toward said roll assembly so that said plural resistance members supported by said each stanchion are located within said concave portion at radially outward parts thereof with respect to said roll assembly (16). An abrasive type vertical grain milling machine according to Claim 1, further comprising plural bran removing chambers, each being formed between circumferentially adjacent stanchions. An abrasive type vertical grain milling machine according to Claim 1, wherein said projection amount adjusting means is adapted to be able to make each of said resistance members project radially inwardly until said resistance member is brought into contact with the outer peripheral surface of said roll assembly. An abrasive type vertical grain milling machine according to Claim 1, wherein said roll assembly comprises a plurality of roll elements (14) fitted on the main shaft (3) while being spaced from each other in the vertical direction in which the main shaft extends and adjacent end portions of the vertically adjacent resistance members defines a small gap therebetween at a level of the space between the roll elements. An abrasive type vertical grain milling machine according to Claim 1, wherein said roll assembly comprises a plurality of roll elements fitted on the main shaft wile being spaced from each other in the vertical direction in which the main shaft extends. and adjacent end portions of the vertically adjacent resistance members defines a small gap therebetween at a level where it faces to the outer peripheral surface of one of the roll elements.

Inventors: ARIJI SHIGERU, OKADA YUTAKA, SATAKE SATORU, ARIJI, SHIGERU, OKADA, YUTAKA, SATAKE, SATORU
Applicants: SATAKE ENG CO LTD, SATAKE CORPORATION
Application year: 1994
Main classification: B02B3
IPC codes: B02B3